"No user-servicable parts inside", my left foot!

Obviously I disconnected it from the grid #electricity first, wore nonconductive footwear, and put only one hand at a time inside the case. If the unit had been in use recently I'd have discharged the big caps, too.

Needed my collection of extra-long security screwdrivers to get into the case - the manufacturer used two different screw heads, just to mess with everyone else's.

But the UPS is now humming happily with a #diy 6S LiPo #battery pack, and the "Aliexpress Special" BMS i used is capping the charging voltage at 4.133 volts (always check).

No more low-capacity, leak-prone, "sudden-death" prone Lead-Acid for this puppy!

:)

If anyone asks, it was like this when I bought it, and I bought it from a guy in a pub. :-p